In a conventionally known process for producing HFC-134a, trichlene is reacted with HF. The process is not accomplished in a single step, but effected by a two-step reaction in which the respective steps use different reaction conditions. This process comprises a first step reaction for reacting trichlene with HF to form 1,1,1-trifluoro-2-chloroethane (hereinafter referred to as "CF.sub.3 --CH.sub.2 Cl" or "HCFC-133a") and a second step reaction for reacting the HCFC-133a with HF to form HFC-134a.
The first step reaction represented by the following scheme (1): EQU CHCl.dbd.CCl.sub.2 +3HF.fwdarw.CF.sub.3 --CH.sub.2 Cl+2HCl (1)
is carried out, for example, under conditions of a pressure of 4 kg/cm.sup.2 G, a temperature of 250.degree. C., and an HF/trichlene molar ratio of 6/1.
The second step reaction represented by the following scheme (2 ): EQU CF.sub.3 --CH.sub.2 Cl+HF.fwdarw.CF.sub.3 --CH.sub.2 F+HCl (2)
is carried out, for example, under conditions of a pressure of 4 kg/cm.sup.2 G, a temperature of 350.degree. C., and an HF/HCFC-133a molar ratio of 4/1.
In consequence, the prior art process comprises the steps of conducting the first step reaction under the above-described conditions, purifying the product to separate the HCl, re-adjusting the reaction conditions, conducting the second step reaction to yield HFC-134a, and then purifying and recovering the HFC-134a. This process has had a disadvantage that the distillation and separation steps are time-consuming, resulting in poor energy efficiency, due to the two reactions conducted under different conditions and each requiring its own distillation/separation step.